This invention pertains, in general, to overshot-type waterwheels and more particularly, to a waterwheel with an axial length substantially greater than the diameter and containing a speed-increaser gear unit and electric generator internally contained within the waterwheel. This assembly is supported by a platform spanning the full length of the waterwheel, which also supports an adjustable chute extending from the dam crest to the waterwheel for the length thereof. The above-described assembly is adjustable vertically by hydraulic cylinder units which raise the waterwheel above the tailwater elevations to prevent the tailwater from causing added rotating friction. Such waterwheel installations are applicable typically at low head sites. Should the dam and spillway length be too long for a single unit, multiple units may be installed.
At present and in the recent past, hydroelectric installations using low-head dam sites, such as those typically less than 15 feet when measured vertically from headwater to tailwater, have generally been unable to economically develop commercial power. The limited number of installations of this type which have been developed either had a subsidy, special power rates, very unusual site conditions, or proved to be economic failures. The hydraulic turbines currently being manufactured are usually custom-designed and are very expensive per unit of power output due to their complex designs which require such items as trash racks, flume or penstock, intake gate, speed-increaser and generator, powerhouse, tailrace and possibly other auxiliary equipment. Existing dams are typically most economical to develop but they also require either an opening through or around the dam or a syphon intake. Each of these items adds substantially to the cost.
To illustrate the present state of the art to which the present invention pertains, the following patents are cited as representative of the current state of the art on the subject of the present invention and over which this invention comprises an advance in the art of power generation:
U.S. Pat. No. 1,061,399 Osborne 1913 PA0 U.S. Pat. No. 1,529,824 Adelmann 1925 PA0 U.S. Pat. No. 4,053,787 Diggs 1977 PA0 U.S. Pat. No. 4,224,793 Gutsfeld 1980 PA0 U.S. Pat. No. 4,296,602 Hales et al 1981 PA0 U.S. Pat. No. 5,082,423 Morgan 1992